We present randomized wait-free lock implementations that are simple and time- and space-efficient. One of them uses only three shared variables and has expected step complexity O(κ log2 κ), where κ is the maximum point contention. The other ones have optimal expected step complexity O(κ), but require O(log n) space, where n is the number of processes in the system. All of our algorithms can be easily implemented on standard hardware that supports compare-and-swap and fetch-and-increment/decrement operations.